Abstract
A full characterization of reversible long-period fibre gratings produced through the wind of a string around a fibre/grooved tube set is presented. This technique enables a good control over the gratings isolation loss-peaks and has high repeatability. The tunability of the resonant wavelengths through the etching of the fibres cladding, prior to perform the gratings, have been investigated. These mechanically induced long-period fibre gratings have shown high sensitivity to loads.

Abstract
In this paper we present and evaluate the spectral response of uniform gratings written in different tapered core sections of single mode fibre. This combination of uniform gratings and tapers leads to three, types of Chirped Fibre Bragg Gratings with different reflection spectra and different mechanical properties. These devices are characterized in function of the applied strain, showing interesting chirp tunability.

Abstract
The development of modern molecular genetic techniques has allowed breast cancer researchers to clarify the multistep model of breast carcinogenesis. Laser capture microdissection coupled with comparative genomic hybridisation and/or loss-of-heterozygosity methods have confirmed that many pre-invasive lesions of the breast harbour chromosomal abnormalities at loci known to be altered in invasive breast carcinomas. Current data do not provide strong evidence for ductal hyperplasia of usual type as a precursor lesion, although some are monoclonal proliferations; however, atypical hyperplasia and in situ carcinoma appear to be nonobligate precursors. We review current knowledge and the contribution of molecular genetics in the understanding of breast cancer precursors and pre-invasive lesions.

Abstract
In this contribution we propose an alternative approach to the traditionally used apodized chirped fiber Bragg gratings for dispersion compensation applications. The unchirped grating proposed has a refractive index perturbation with varying negative mean, acting simultaneously as optical filter demultiplexer and efficient group velocity dispersion compensator in wavelength division multiplexing systems.

Abstract
We compare the thermal tuning capabilities of two type I gratings written in unloaded and in hydrogen-loaded germanium-doped silica fibers, and a type IIa grating written in unloaded fiber. The hydrogen-loaded grating is annealed after writing, to remove any unreacted hydrogen. We further study the gratings' response stability with temperature, an important property when these devices are used as optical filters in wavelength division multiplexing systems. Experimental results show that the worst option is the type I grating in unloaded fiber, which presents the highest bandwidth and group delay variations with temperature, so that it is the least suitable as a thermotunable optical filter in wavelength-multiplexed systems. For the other two options, the bandwidth and group delay variations are much smaller, the lowest values being obtained with the hydrogen-loaded type I grating, and the best thermal tuning efficiency with the type IIa grating. (C) 2003 Society of Photo-Optical Instrumentation Engineers.

Abstract
Bragg gratings written in high-birefringence fibre optics are a key element in the simultaneous measurement of transversal strain components and temperature, and they have several applications as single polarisation optical filters for wavelength division multiplexing (WDM) applications. Precise determination of grating characteristics is needed to aid device design, particularly taking into account the polarisation of the illuminating light. The authors report results concerning the production and characterisation of Bragg gratings in high birefringence fibre. Birefringence is measured by the wavelength dependence of the beat length, and from the Bragg grating reflection bands, for three common high birefringence fibres. Characterisation of the gratings when subjected to transversal strain and temperature is described, as well as results of the use of the grating to measure, simultaneously, those two parameters.